In our journey through the Solar System, we have
not talked about one very important member, the King of the Solar
System our Sun.

What is the Sun?

It is important that we understand what the Sun is,
because it helps us to better understand our own place in the
Universe. For thousands of years people thought that the Earth
was at the center of the Universe. The Sun, they thought, was a
unique ball of fire found nowhere else.

In modern times we have discovered that the Sun is
not unique at all. It is just one star in a universe with
trillions of other stars. The Sun is a normal star just like
every other star in the sky.

Many of the stars in our sky have names, such as
Antares and Betelgeuse. Similarly, the Sun also has a name.
The name of our sun is Sol. Think about that for a
moment. Why does that name sound familiar? Our planet
sits in the Solar System, or the System around the star Sol.
Would another star's planets be in a Solar System? No, each
star's system is named after the star. If Antares has a system,
its name would be The Antares System.

Convection:

The sun has three layers. The first layer is
a super hot core where hydrogen fuel is burned into helium. On
top of the core lies a thick layer of churning gases. Finally,
above this sits a thin surface.

The churning which takes place in the middle layer
is also called convection. The hot gases rise up to a certain
point. As they rise they cool down. Eventually they
become so cool that they begin to sink again deeper into the Sun
where they slowly heat up. Then the process starts all over
again. Just like a spinning wheel, the gases in this layer are
always churning up and down in giant circles.

Magnetic Field:

This convection creates a huge magnetic field
around the Sun. In other words, it turns the Sun into a giant
magnet. This magnetic field is what causes Sun spots as well as
Solar flares. Incidentally, the same thing happens here on
Earth. As the molten lava under the Earth's crust churns up and
down it creates a magnet. This is why a compass always
points North.

Sun Cycles:

The Sun follows an eleven year cycle. Over an
eleven year period it slowly gets more and more active. As the
eleven years go on we see more and more Sun spots, solar flares, and
solar storms which send atomic particles at the Earth. Then
suddenly, after eleven years, the cycle starts all over again.
Right now we are at the height of the cycle, meaning that the Sun is
covered with many Sun Spots. It also means that occasionally
our satellite systems go out. Solar storms can cause
disturbances in satellites making them useless for a few hours, or days.

Is the Sun big?

Compared to everything else in the Solar System the
Sun is huge. It is so big, that if it were hollow you could fit
one million Earths inside of it. The Sun contains 99.9% of all
the mass in the Solar System.

However, while it is true that the Sun is bigger
than anything else in our Solar System and also bigger than most of
the stars in the Universe, compared to other stars the Sun is not
large. It is a middle sized star.